Our studies are geared at gaining an understanding of the hormonally mediated molecular mechanisms by which sperm maturation, sperm survival, and epididymal function are regulated. We are engaged in studies on androgen and estrogen receptors in the cytoplasm and nuclei of sexually mature and immature rabbits. We have determined that a cytoplasmic androgen receptor can be detected in castrated rabbits and that the receptor moves to the nucleus in a time and temperature dependent manner. We are examining the enzyme 5 alpha-reductase in epididymal tissue and the hormonal regulation of the enzyme. We will be studying androgen receptor activity and 5 alpha-reductase activity in the epididymis during development. The androgen receptor is distinct from testicular androgen binding protein (ABP) in several regards, and we are exploring these differences further. The immature rabbit epididymis contains a cytoplasmic estrogen receptor which moves to the nucleus. We are also examining developmental changes in ABP concentration in the epididymis. BIBLIOGRAPHIC REFERENCES: "Estradiol Binding in Cytosol from Epididymides of Immature Rabbits ", B. J. Danzo, B. C. Eller, L. Judy and J. Trautman, Molec. Cell. Endocr. 2, 91 (1975). "The Effects of Efferent Duct Ligation on 5 alpha-Dihydrotestosterone Binding and Sperm Maturation", B. J. Danzo, B. C. Eller, M.-C. Orgebin-Crist and T. G. Cooper, in Workshop on Male Fertility Control, J. J. Sciarra, C. Markland and J. J. Speidel, Eds., Harper and Row, (1975) p. 89.